This section introduces aspects that may be helpful in facilitating a better understanding of the invention. Accordingly, the statements of this section are to be read in this light and are not to be understood as admissions about what is in the prior art or what is not in the prior art.
When performing joint processing (JP) of uplink coordinated multi-point transmissions (so-called COMP), one has to deal with multi-path propagations leading to different timing/propagation delays to the different reception points (e.g. base stations) of a COMP coordination cluster. If the difference of the timing offsets due to the different propagation delays exceeds the length reserved for the cyclic prefix in an Orthogonal Frequency Division Multiplex, OFDM, transmission scheme, the joint processing of the uplink signals of different COMP reception points (for example located in different base stations (BS), such as enhanced NodeBs “eNBs”) in a single receiver is no longer possible.
For this reason 3GPP has defined two different cyclic prefixes (CP), a normal and an extended one. To allow for joint processing, the length of the extended cyclic prefix can be configured to allow for a corresponding maximum difference of the timing offsets (delay spread) of the uplink radio signals received in the different reception points. However, using such an extended cyclic prefix has the disadvantage of generating an additional overhead, which reduces the achievable overall uplink throughput. With the normal cyclic prefix, 14 OFDM symbols can be used for the transmission within one sub-frame of the duration of 1 ms. Using the extended cyclic prefix allows for only 12 OFDM symbols per sub-frame. Using the extended cyclic prefix instead of the conventional cyclic prefix thus results in a throughput reduction that amounts to about 20 percent.